Method of sensitizing photographic silver-halide emulsions



Feb. 18, 1947. A. w. ANlsH 2,415,927 METHOD oF sENsITIzING PHoToGRAPHIcSILVER-HALIDE EMULsIoNs Original Filed Oct. 17, 1944 Patented Feb. 18,1947 UNITED STATES PATENT OFFICE METHOD OF SENSITIZING PHOTOGRAPHICSILVER-HALIDE EMULSION S Alfred W. Anish, Johnson City, N. Y.,4 assignerto General Aniline & Film Corporation, New

York, N. Y.. a corporation of Delaware Original application October 17,1944, Serial No. 559,134. Divided and this application October 17, 1944,Serial No. 559,133

4 Claims.

these dyes, however, the substitutions at the central carbon atom of thepolymethine chain do not enter into a resonance conguration so as to actas an auxochromic group.

An object of the present invention is to provide new chain-substitutedcyanine dyes and salts thereof, containing a carbonyl or thiocarbonylgroup as a part of the chain substitution.

A further object is to provide a photographic element comprising anemulsion sensitized with new chain-substituted cyanne dyes and saltsthereof, containing a carbonyl or thiocarbonyl group as a part of thechain substitution.

Other objects and advantages of this invention will become apparent byreference to the following specification in which its preferred detailsand embodiments are described.

This invention is based on the discovery that sensitizing dye bases ofthe polymethine series, having introduced in the alpha-carbon atom ofthe polymethine chain a carbonyl or thiocarbonyl group, are suitable forsensitizing photographic emulsions. In particular, they are especiallyuseful for sensitizing silver-chloride emulsions. This latter unexpectedand highly desirable property makes the sensitizing dye bases applicableto the varicontrast printing process. It is believed that the carbonylor thiocarbonyl group enters into the resonance configuration, acting asone of the auxochromic groups.

The dye bases, which may be used as such or in the form of theirquaternary ammonium salts, are prepared by condensing an omega acylazole with a cyanine dye intermediate, and are characterized by thefollowing general formula:

wherein R represents an alkyl, e. g., methyl, ethyl, propyl, butyl andthe like, carboxyalkyl, e. g., carbomethoxy, carbethoxy, carbopropoxyand the etc., alkoxya1kyl,e. g., methoxyethyl, ethoxypropyl, etc., aryl,e. g., phenyl, naphthyl, diphenyl, anthranyl, alkoxyaryl, e. g.,methoxyphenyl, ethoxyphenyl, propoxyphenyl, methylenedioxyphenyl and thelike, aralkyl, e. g., benzyl, methylbenzyl, ethylbenzyl, propylbenzyl,etc., R1 represents an alkyl or alkoxyalkyl of the same value as R, Wand W are the same or different and represent hydrogen, alkyl,carboxyalkyl, a1- koxy, alkoxyalkyl, aryl, substituted aryl and aralkylgroups of the same value as R, X and X' are the same or diierent andrepresent oxygen, sulfur, selenium or RII wherein R and R may be analkyl or an aryl group ci the same value as R, and Y represents eitheroxygen or sulfur, and n represents an integer of 4from one to two.

The omega acyl azoles used in the preparation of the new dyes of thepresent invention are described in U. S. Patents 2,166,198, 2,323,504and 2,233,873. These compounds consist, for the most part, of one ormore ring systems in each azole nucleus, which azole nucleus contains agroup directly attached to the nucleus through the methylene radical.The benzthiazole-2- .substituted lcyanine `dye 3 pyruvic ethyl esterused in the preparation of the new dyes of the present invention isprepared according to the method of Borsche and Doeller, Liebigs Annalendes Chemie, vol. 537, pages 56- 58, 1938.

The methods for the preparation of the cyanine dye intermediates, e. g.,2(acetanilido vinyl) cyclammonium quaternary salts are given in theliterature. One general method consists of reacting a cyclammoniumquaternary salt such as 2-methyl benzthiazole with an excess of diphenylformamidine in acetic anhydride to give 2(5- acetanilido vinyl)benzthiazole.

Typical cyanine dye intermediates which can be employed iin `thecondensation react-ion with an omega acyl azole include: ZQS-atanilidovinyl) cyclammonium Quaternary salt, 2in-anilino--ethyl-vinyl)cyclammonium quaternary salt, 2(4-acetanilido butadienyl) .cyclammoniumquaternary salt, 2(ethy1mercapto) t.cyelammonium quaternary salt andZQS-ethyhnercapto- -ethyl-vinyl) cyclammonium-salt.

In preparing the novel 'sensitiaing dyes ofthe present invention, 1 molof an omega acylazole is heated with 1 mol of ,a-cyanine dyeintermediate under reux conditionsiin the presence of a basic (acidbinding) condensing agent such as pyridine, methyl pyridine, dimethylpyridine, ethyl pyridine, ethylmethyl pyridine, trimethyl pyridine,quinoline andf the like, using basic cata- Vlysts such -as,triethyl'amine or potassiumcarbonate,or in thefpresence ofan acid condensingagent such as acetic acid or acetic anhydride, etc. Thesefcondensingagentsassuch act assolvents for the reactants and as catalyticcondensing or binding agents. 'In'generaL theamountof condensingfagentused may vary within wide limits, e. g., rom'l to 25 mols.Concentrations ranging from aboutV 1 mol to about 15 mols are preferred.

,'Iheresulting, product obtained by condensing an omega acyl azole'witha cya-nine dye inter- V:mediate may-be, if desired, quaternizedaccording .to well-known methods to give a dye salt. The fdyesalt,thuseobtained is readily converted into 1ay differentsaltrby treatingit in solution with an VYaqueous solution of a salt containing thedesired anion-'such as,.for-. example; potassium: bromide or dodide.

The diagrammatic spectrograms, constituting theaccompanying drawing,illustrate the regions .of the spectrum to which the varioustypes ofchain bases and salts thereof, `containinga kcarbonyl orthiocarbonylgroup as va part of the chain'substitution disclosed herein,

thiazolylidene) lpropenyll benzthiazole.

The following .examples describe in detail the methods for accomplishingthe above objects, but it is to be understood that they are insertedmerely fforithe purpose of illustrations `and are not to be construed-asylimiting the scope of-theinvention.

VA4A) @willesensitize a gelatine .silver-halide emulsion` o Ewample Iy.223 gms. Lof. Zic-acetanilido avinyl) benzthiazole ethiodide and 1.3gms. of 2-phenacyl-benzthiazole were dissolved in 20.0 cc. of drypyridine and 0.5 cc. of triethylamine added. The mixture .wasrefluxedfor 11/2 hours, then water added to 'make' it slightly cloudy. Thecrystals which separatedfout were Washed with water and alcohol,-andznallyzboiled. out with ethyl alcohol.

-The.dyesensitized a chloride emulsion rather strongly and a .bromideemulsion weakly. The alcohol solution of the intermediate had anabsorption maximum at about 500 mp. An alcohol solution ci 25 mg. of thedye was incorvvporated in l kilogram of silver chloride emulsioncontaining a small amount of silver bromide and .havinga total contentof :Li-5% silver-halide. l,The dye imparts YazsensitivityitoAabout'600my., with `a maximum ,sensitivityat about L55() mtu-whichis'at.

Example II Four and one-half gms. of 2(acetanilido vinyl) benzthiazole:ethiodide and 1.6 gms. of Z-aoetonyl benzthiazole .were dissolved in40.0 cc. of drypyridine to which 1.0l cc. oftriethylamine had beenadded. :The mixture was heated at C. for 2 hours, while still warm 40cc. of water--Were ,addedand after standing dye crystals separated.rThe-dye ibase lwas filtered ofi and `washed withv dilute alcohol.Vlt'lwasfurther puriiied by boiling out .with-ethyl alcohol.

The;alcoholfsolution of :the intermediate jhad an :absorption 'maximumat about -510 nip. .An

A:alcoholsolution-:of '30 mguof the ydye was incorporated in'lkilogram-.oi silver .chloride emulsion containing: a; small amount ofsilver bromide and having a total content .of @5% ,silver-halide.The1dye imparts la sensitivitytoabout 600m, with .a maximumfsensitivityat l.about 560111,

which is flat.

Example III 0.9 gm. of i1-3 acetbutadienyl benzthiazole ethiodide and0.9 gm. of 2acetonyl benzthiazole were dissolved in 15.0 cc. of drypyridine and 0.5 cc. of triethylamine added. The mixture stood at roomtemperature for 3 to 4 hours. The reaction was then completed by heatingat 50-60 C. for 2 hours. The dye was precipitated with Water andfiltered after standing another 3-4 hours. The lter residue Was taken upin dioxane and diluted with ethyl alcohol. The pure dye separated onstanding. The dye sensitized a chloride emulsion rather strongly and abromide emulsion weakly.

` The alcohol solution of the dye had an absorption maximum at about 560mit. An alcohol solution of 40 mg. of the dye was incorporated in 1kilogram of silver chloride emulsion containing a small amount of silverbromide and having a total content of 4-5% silver-halide. The dyeimparts a sensitivity to about 680 ma, with a maximum sensitivity atabout 630 mit, which is at.

Example IV OCHs 1.1 gms. of 2(acetanilldo vinyl) benzthiazole ethiodideand 0.7 gm. of 2(pmethoxybenzoyl) Were dissolved in 10.0 cc. of drypyridine and 1.0 cc. of triethylamine added. The mixture was heated at100 C. for 21/2 hours, then cooled and diluted out with Water. Thecrystals which separated were ltered, Washed with Water and crystallizedfrom ethyl alcohol in two fractions. The more insoluble portioncontained the pure dye;

The alcohol solution of the dye had an absorption maximum at about 500m/i. An alcohol solution of 30 mg. of the dye Was incorporated in 1kilogram of silver chloride emulsion containing a small amount of silverbromide and having a total content of 4-5% silver-halide. The dyeimparts a sensitivity to about 600 me, with a maximum sensitivity atabout 540 my, which is at.

Example V2-[1-(3,4)-methylenedioxybenzoyl-3-(8-ethyl-2(3)-benzothiazolylidene Ypropenyl] benzthiazole O C H2 `0;5 gm. of 2 acetanilido vinyl)benzthiazole ...ethiodidel and 0.3` gm. yof 3,4 methylenedioxybenzoylethyl acetate were dissolved in 10.0 cc. of dry pyridine and 0.25 cc. oftriethylamine added. The mixture was reuxed for 10-15 minutes, cooledand water added. After standing for several hours, crystals separatedout. The crude dye was recrystallized from ethyl alcohol in twofractions. The pure dye was contained in the more insoluble fraction.

The alcohol solution of the dye had an absorption maximum at about 500me. An alcohol solution of 40 mg. of the dye was incorporated in 1kilogram of silver' chloride emulsion containing a small amount ofsilver bromide and having a total content of 4-5% silver-halide. The dyeimparts a sensitivity to about 600 me, with a maximum sensitivity atabout 540 mf, which is flat.

Example VI 2-[l-acetyl-S-(3-ethy1-2(3)-benzothiazolylidcne)propenyl]benzoxazole 4.5 gms. of 2(acetanilido vinyl) benzthiazole ethiodide and2.0 gms. of 2-acetonyl benzoxazole were dissolved in 30 cc. of drypyridine and 1.0 cc. of triethylamine added. The mixture was reuxed for20 minutes and then diluted with Water. The crystals which separated outwere filtered 01T, washed with Water and recrystallized in two fractionsfrom ethyl alcohol.

The alcohol solution of the dye had an absorption maximum at about 500ma. An alcohol solution of 40 mg. of the dye was incorporated in 1kilogram of silver chloride emulsion containing a small amount of silverbromide and having a total content of 4-5 silver halide. The dye impartsa sensitivity to about 600 me, with a maximum sensitivity at about 540ma, which is at.

Example VII 2-[l-acetyl-B-(3-ethyl-5,6-dimethyl-2(3)-benzoxazolylidenepropcnyll benzthiazole CH3 S 2.0 gms. of 2-acetonyl benzthiazolavand 5.0gms. of 2(acetanilido vinyl) 5,6-dimethyl benzoxazole ethiodide weredissolved in 30.0 cc. of dry pyridine and 2.0 cc. of triethylamineadded. The mixture was refluxed for 20 minutes and water added whilestill hot. On standing, crystals separated Which were iiltered off,Washed with Water and then recrystallized from methanol.

The alcohol solution of the dye had an absorption maximum at about 500mit. An alcohol solution of 25 mg. of the dye Was incorporated in 1kilogram of silver chloride emulsion containing a small amount of silverbromide and having a total content of 4-5% silver halide. Thedyeimparts'a sensitivity to about 600 ma, with a maxi- Imum sensitivityatl about 550 which is, dat,

dry Vpyridine' andV 2.0 cc.

2:0l gms.l of 2-acetonyl benzthiazole .and 5.0 gms'. of. 2 acetanilidovinyll-G-ethoxy-benzse- -lenazole etlliodide were dissolved in 30.0 cc.of of triethylamine added. The mixture was reiiuxed for minutes andwater added while still hot. The crystals which separated on standingwere filtered oil, washed with Water and recrystallized in two partsfrom methanol.

The alcohol solution of the dye had an ab' sorption maximum at about 590ma. An alcohol solutionof mg. of the dye was incorporated in l kilogramof silver chloride emulsion containing a small amount of silver bromideand having a total content of 45% silver halide. The dye imparts asensitivity to about 690 ma, with a maximum sensitivity at about 64:0`ma, which is ilat.

\ -oom One gramof 2 acetanilido vinyl) --methoxyLbenzthiazole ethiodideand 0.4 gm. of 2-acetonyl benzthiazole were dissolved in 20.0 cc. of drypyridine and 0.5 cc. of triethyl'arnine added. vThe mixture Was refluxedfor 1 hour and water added. The dye crystals which separated on standingwere Washed With water, dissolved in hot dioxane and diluted out withmethyl alcohol. The crystals which-separated were Washed with water andboiled out With ethyl alcohol.

The alcohol solution of the dye had an absorption maximum at about 500my. An alcohol solution of mg. of the dye was incorporated in 1kilogramy of silver chloride emulsion containing a smally amount ofsilver bromide and having a total content of 45`% silver halide. The dyeimparts a sensitivity to about 600 ma, with a maximum sensitivity atabout 590 my, which is flat.

8 with water and the ldye crystals purl'ed from methyl alcohol.

The alcohol solution ofthe dye Vhad-ran absorption maximum at about 500mit. An alcohol solution of 4:0 me. of the dye Vwas incorporated in lkilogram of silver chloride emulsion containing a small amount oi silverbromide` and having a total content ofy 4-5% silver-halide. The dyeimparts a sensitivity to about 560 mp, with a 3.5 gms. of Z-acetonylbenzthiazole ethiodide was mixed with 4.5 gms. of 2(acetanilido vinyl)xbenzthiazole ethiodide, and 30.0 cc. of dry pyridine and 1.0 cc. oftriethylamine added. The mixture was reuxed for 20 minutes and the dyeprecipitated with Water. The dye crystals were filtered od andrecrystallized from ethyl alcohol.

The alcohol solution of the dye salt had an absorption maximum at about570 ma. An alcohol solution of 30 mg. of the dye was incorporatfrom theacid solution. 75

ed in l kilogram of silver chloride emulsion containing a small amountof silver bromide and having a total content of 4-5% silver-halide. Thedye imparts a sensitivity to about 640 mit, with a maximum sensitivityat about 610 ma, which is flat.

While the above example has been described particularly with referenceto the preparation of a dye salt, it will be understood that the dyelbases in the preceding and4 subsequent examples may also be transformedinto dye salts by methods known to the art. The dye salts, however, showa bathochrcmic shift under the same' conditions of application over thedye bases from which they are derived.

Example XII nzthiazole C O O 02H5 l gram each. of benzthiazole 2-pyruvicacid ethyl ester and 2(acetanilido vinyl) benzthiazole ethiodide Weremixed in 15.0 cc. of dry pyridine and 4,-5 drops of triethylamine added.The mixture was reluxed on an oil bath for 30 minutes, cooled and Wateradded until slightly cloudy. The filtered dye crystals were washed withwater and recrystallized from ethyl alcohol.

The alcohol solution of the dye had an absorption maximum at about 500ma. An alcohol solution of #i0 ing. of the dye was incorporated in 1kilogram of silver chloride emulsion containing a small amount of silverbromide and having a total' Lcontent of 4-577-sllver-halide. 'The'dyeimpartsa sensitivity tof about 590 my., witha 9 maximum sensitivity atabout 540 ma, which is flat.

Emample XIII ooooZHs s 1 gram each of -naphthiazole 2-pyruvic acid ethylester and 2 acetanilido vinyl) benzthiazole ethiodide were dissolved in15.0 cc. of dry pyridine and 0.5 cc. of triethylamine added. The mixturewas reiluxed for 30 minutes, cooled and diluted out with water. Thecrystals which separated were filtered and Washed several times Withalcohol and boiled out twice with methanol.

The alcohol solution of the dye had an absorption maximum at about 500mn. An alcohol solution of 30 mg. of the dye w-as incorporated in 1kilogram of silver chloride emulsion containing a small amount of silverbromide and having a total content of 4-5% silver-halide. The dyeimparts a sensitivity to about 600 mfr, with a maximum sensitivity atabout 500 ma, which is flat.

Eample XIV (gzHs One gram of 2-thioacetonyl benzthiazole, prepared byfusing 2-acetonyl benzthiazole with phosphorus pentasulde at 120 C., washeated at 100 C. with 1.4 gms. of 2- -acetanilido vinyl benzthiazole in10.0 cc. of dry pyridine and 1.0 cc. of triethylamine for 11/2 hours.The reaction mixture was diluted out with cc. of water and on standingcrystals of dye separated out. These crystals were filtered oi anddissolved in 10 cc. of dioxane and then diluted with 30 cc. of ethylalcohol. Twenty cc. of water was added and on standing the dye separatedout as brown-red crystals.

'Ihe alcohol solution of the dye had an absorption maximum at about 510ma. An alcohol s0- lution of mg. of the dye was incorporated in 1kilogram of silver chloride emulsion containing a small amount of silverbromide and having a total content of 4-5% silver-halide. The dyeimparts a sensitivity to about 600 ma, with a maximum sensitivity atabout 560 ma, which is iiat.

In the preparation of emulsions containing these chain substitutedcyanine dye bases and dyes, the base or dye may be dissolved in methylor ethyl alcohol and a volume solution containing from 5 to 50milligrams of the dye base or dye added to a liter of emulsion. While ingeneral practice it may not be necessary to add the dye base or dye inthe amounts larger than those above given, generally, for satisfactoryresults, amounts usually ranging from 5 to 25 milligrams are suiiicientto obtain the maximum sensitiz- (Sil ing eiect.` However, I do not wishto limit my invention to the quantities just indicated, the mostsuitable amount will in each case be found by a few comparativeexperiments. The dye bases or dyes may be added to the emulsions in formof solutions. Suitable solvents as indicated in the examples are thealcohols, for instance, methyl or ethyl alcohol, which may be anhydrousor diluted with a small volume of water. In aotual practice, the dyebases and dyes are applied to the emulsion during any stage of itsproduction, however, they are preferably added to the nished emulsionbefore being cast.

It will be understood that Where in' the claims appended hereto the termdye is used, that such is intended to include the dye salt. l"

This application is a division of my co-pending application Serial No.559,134, led on even date.

While'there have been pointed out above certain preferred embodiments ofthe invention, the same is not limited to the `foregoing examples,illustrations, or to the specific details given therein, but is capableof variations and modications claims in which it is intended to includeall features of patentable novelty residing therein.

I claim:

1. A photographic gelatino-silver-halide emulsion which contains acompound selected from the group consisting of compounds of the generalformula:

and the Quaternary ammonium salts thereof, wherein R represents a memberselected from the class consisting of alkyl, alkoxy, alkoxyalkyl,carboxyalkyl, aryl, aralkyl and alkoxyaryl radicals, R1 represents amember selected from the class consisting of alkyl and alkoxyalkylradicals, W and W are substituents selected from the class consisting ofhydrogen and radicals of the same value as R, X represents a memberselected from the class consisting of oxygen, sulfur and selenium, Xrepresents a member selected from the class consisting of oxygen,sulfur, selenium and RII where Rf and R" 3. A photographicgelatino-silver-halide emul- 11* sion whichxcontainsa. cyaninedyeftheiollovsl-f` ing-,str11cture:. n

o--CH 4, A, photographic.,gel21.121110ysilver-hande?smul.E 15f sionwhich contansLacyanne-dyesalt oithefffolf IUWing-,structurez REFERENCESCITED The following references are. of record in the le of this patent:

UNITED STATES: PATENTS Number s., s: 2,158,287 ru, GQ. f o 2,169,434 :L1 2,345,094v (b-GH @12:0 K 1,942,854

Name Date Konig May 16, 1939 Schwarz- ...Aug. 15, 1939 Brooker et a1.Mar. 28, 1944 Brooker Jan. 9, 1934

